In the weaving of textile fabrics in the textile industry, it is conventional practice for a filling yarn to be introduced from one side of the loom (hereinafter referred to as the right hand side, even though some looms introduce filling yarn from the left hand side). For this purpose a plurality of packages of yarn are stored at or near the right hand side of the loom, and the rapier or air jet weft insertion system carries the weft yarn across the weaving shed. Conventional filling or weft introducing apparatuses contain a cutting apparatus to cut the yarn on the side from which it is fed and provide a trimmed selvedge on this side. There is also formed on the opposite side of the fabric (hereinafter the left hand side of the loom), a selvedge which must be trimmed away. There are known in the prior art trimming apparatuses for trimming this "left hand selvedge" also. However, generally such left hand selvedge trimmers are operated from cams and utilize gears, springs, auxiliary shafts, and the like which add considerable cost and complexity, and potentially reduce the reliability of the selvedge trimming operation. A representative sample of selvedge trimming apparatuses are disclosed in the following patents:
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 2,226,069 E. Nadeau 12/24/40 3,402,744 V. Scherillo 9/24/68 3,613,741 A. Ravella 10/19/71 4,134,434 J. Malasek 1/16/79 4,185,667 E. Kendrick 1/29/80 4,296,783 E. Ichimatsu 10/27/81 ______________________________________
Rather than operating the "left hand" selvedge trimmer from cam shaft or utilizing separate timing devices to activate the selvedge trimmer, it would be advantageous if this selvedge trimmer could be operated by the arcuate reciprocal motion of the lay or sword system for the lay. Attempts to accomplish this have generally met with little success, however, because conventional lay activating systems utilize a relatively large pivot arm (long sword), and the stroke is too long to provide a reliable cutter stroke for the selvedge trimmer. Further, the impact of the lay on the trimmer mechanism is likely to damage the trimmer apparatus or the lay due to the high impact forces imparted.
In accordance with the present invention, however, it has been found that in a "short sword system" (where the rocker shaft is positioned higher in the framework of the loom nearer to the lay than in conventional systems), operation responsive to the lay is possible. The combination of the short sword system and a unique type of linkage between the rocker shaft and the trimmer mechanism are utilized in the present invention to effect a successful "left hand" selvedge trimming operation which is operated responsive to the arcuate reciprocal motion of the rocker shaft. Toward this end, a "four bar linkage" concept is utilized to connect the rocker shaft with the cutter support shaft which supports the movable blade of the selvedge trimmer. This linkage so connects the rocker shaft with the cutter blade, that the relatively large, abrupt movement of the rocker shaft is reduced to a smooth pivotal movement of the shaft which supports the cutter blade. Further, the linkage is so constructed as to avoid any obstructions which naturally occur between the rocker shaft and the trimmer mechanism. The relatively strong reciprocal movements of the lay during the beat up operation are thus converted to smooth trimming strokes of the cutter blade to effect the selvedge trimming responsive thereto.
It is therefore an object of the present invention to operate the "left hand" selvedge cutter directly from the reciprocal motion of the lay in a short sword weaving system, whether the short sword system being utilized is on shuttleless loom or an air jet loom.
It is another object of the present invention to provide a "left hand" selvedge trimming mechanism of the type described in which a "four bar linkage" connects the rocker shaft of the short sword system to the cutter blade support shaft of the trimming mechanism to reduce the abrupt long strokes of the lay sufficiently to operate the selvedge trimmer.